This invention relates to storage resource management in a computer network, and more particularly to distributed storage management in a storage area network (SAN).
The emergence of fibre channel as a networking technology designed specifically for storage resources has been a primary impetus in the ongoing development of SAN technology in enterprise computing environments. These technologies, coupled with the changing needs of users, are causing the demand for storage to accelerate. Consequently, this has increased the basic requirement of managing, storing, and accessing storage resources in a SAN.
A SAN interconnects different kinds of storage resources with associated data servers on behalf of a larger network of users represented by client computers. Typically, the SAN uses fibre channel technology to facilitate high bandwidth communication between the storage resources and the data servers. The storage resources are usually implemented using physical data storage configurations such as Redundant Arrays of Inexpensive Disks (RAID), simple disk arrays, and complex disk subsystems. The data servers manage the storage resources using a traditional volume manager comprising a data access portion and a data management portion. The data management portion is responsible for managing the physical data storage devices including abstracting the physical device and presenting to the client computer user a logical unit of storage called a volume. The data management portion also is responsible for backup and restore, data migration from one storage device to another, and the sharing of data. In contrast, the data access portion of the volume manager is responsible for converting the logical data requests issued by the clients into data transfer operations directed to the physical storage corresponding to the logical device. Once the physical data blocks corresponding to the requested logical blocks have been retrieved, the server handles the data transfer over the fibre channel and delivers the blocks to the client computer.
However, sharing storage resources using a SAN infrastructure is currently limited. A typical SAN may interconnect to other computer systems including other networks and servers. While these interconnections allow these systems to share data, it could also lead to not only the possibility of data corruption but also to an increase in the complexity of managing these storage resources. System administrators responsible for managing the SAN and its storage resources are faced with a time consuming and costly management task.
One solution involves the use of zoning, in which a fibre channel switch is placed between storage resources and a computer system. The switch is programmed to grant to the computer system access to the storage resource that has been configured for the port. However, this solution is severely limited because in a large xe2x80x9cfabricxe2x80x9d effective zoning may require the programming of several layers of switches to represent the correct grouping, which can be difficult and prone to error. Moreover, if it becomes necessary to rearrange the cables associated with the fibre channel, this can impact the current access of storage to other computer systems, because the port numbers can change.
Another solution might include placing an intermediate computer between the storage resource and the other computer systems to mediate access to the storage. The intermediate computer intercepts all input/output (I/O) requests flowing to the disks and routes the requests as required. The intermediate computer must be capable of storing and forwarding the requests. To avoid a loss in performance, the intermediate computer must have twice the bandwidth of the incoming fibre channel connection. However, in a multi-port storage topology, the bandwidth requirement increases dramatically, leading to an increase in cost. The intermediate computer does alleviate the management problem by providing the system administrator with a single management console for zoning and virtual volume management. Although the intermediate computer provides attractive management capabilities, it lacks scalability and is costly to implement.
In many enterprise computer environments, the storage resource typically is implemented using different levels of RAID. Although RAID configurations provide improved I/O performance and/or reliability, management can be complex. For example, if an enterprise is running heterogeneous host computer systems, then a system administrator must deal with multiple management interfaces. The RAID volume may need to be modified if any of the components of the RAID have failed or if the administrator has changed the configuration. To avoid downtime when modifying the RAID configuration, it must be rebuilt while online which may impact the I/O performance of the running host computer system and client systems.
In light of the foregoing, a SAN infrastructure that is able to share storage resources by distributing the volume management functions between server computers responsible for data management and client computers responsible for data access would be an improvement in the art.
In a first aspect, the invention provides a method of managing storage resources associated with a computer network. The method includes managing storage resources associated with a network having at least one storage resource coupled to at least one server and at least one client over at least one data path, wherein the client directs I/O requests to the storage resources and redirects I/O requests to the server upon the detection of a failure condition.
In one implementation, the method includes the communication of volume information associated with the storage resource to a client based on the results of the authentication. In yet another implementation, the method includes the allocation of storage space from the storage resource in response to a client request, and the communication of volume information associated with the allocated space to the requesting client. In another implementation, the method comprises the allocation of a new storage space from the storage resource in response to a receipt of a failure condition, wherein the new storage space includes a new virtual disk associated with a new physical storage resource; the initiation of the recovery of the contents associated with the failure condition in cooperation with the new storage space; and the communication of a recovery status to the client, wherein the client and the server continue the recovery based on the recovery status. The method also comprises changing the volume configuration corresponding to the storage resource; committing the changes to the changed configuration during which time the client is excluded from accessing the storage resource; and communicating the new state of the configuration to the client. In another implementation, the method comprises providing a copy of unmodified data blocks before modifying the data blocks; communicating a list of the modified data blocks to a backup process residing on the server, wherein the backup process uses a pseudo-device to read the unmodified and modified data blocks.
In a second aspect, the invention provides a distributed shared resource management system. This system includes at least one storage resource coupled to at least one server and at least one client over at least one data path, wherein the server manages the storage resource over the data path, and the client directs I/O requests to the storage resource and redirects the I/O requests to the server upon the detection of a failure condition. This system is adapted to operate according to the method described above.
In a third aspect, the invention provides an article comprising a computer-readable medium that stores computer executable instructions for controlling a computer in a distributed shared storage resource management system in which system comprises at least one storage resource coupled to at least one server and at least one client over at least one data path, wherein the computer executable instructions cause system to operate according to the methods described above.
With the methods and systems for managing storage resources associated with a storage network disclosed in the present invention, the management of volumes may be advantageously centralized using a common management interface. In addition, storage resources can be shared in a secure environment without requiring an intermediate node. Furthermore, the more complex volume management functions associated with managing the storage resources may be allocated to at least one server, which relieves the client system from performing these tasks. Moreover, client systems may now concentrate on accessing data from the storage resources and offload the recovery process onto the servers which are capable of performing this process efficiently.
The details of various embodiments of the invention including certain preferred embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description, drawings, and claims.